15.1. Insect nuisance and phobia

Our perceptions of nuisance may be little related to the role of insects in disease transmission. Insect nuisance is often perceived as a product of high densities of a particular species, such as bush flies (Musca vetustissima) in rural Australia, or ants and silverfish around the house. Most people have a more justifiable avoidance of filth-frequenting insects such as blow flies and cockroaches, biters such as some ants, and venomous stingers such as bees and wasps. Many serious disease vectors are rather uncommon and have inconspicuous behaviors, aside from their biting habits, such that the lay public may not perceive them as particular nuisances.

Harmless insects and arachnids sometimes arouse reactions such as unwarranted phobic responses (arachnophobia or entomophobia or delusory parasitosis). These cases may cause time-consuming and fruitless inquiry by medical entomologists, when the more appropriate investigations ought to be psychological. Nonetheless, there certainly are cases in which sufferers of persistent “insect bites” and persistent skin rashes, in which no physical cause can be established, actually suffer from undiagnosed local or widespread infestation with microscopic mites. In these circumstances, diagnosis of delusory parasitosis, through medical failure to identify the true cause, and referral to psychological counseling is unhelpful to say the least.

There are, however, some insects that transmit no disease, but feed on blood and whose attentions almost universally cause distress — bed bugs. Our vignette for this chapter shows Cimex lectularius (Hemiptera: Cimicidae), the cosmopolitan common bed bug, whose presence between the sheets often indicates poor hygiene conditions.